W2Mo9Cr4VCo8 (AISI M42) super-hard high-speed steel wires (Φ5.2 mm

Φ4.96 mm) are treated by intermediate annealing

furnace-cooling annealing and phase-transformation annealing

and the effect of different microstructure factors on work hardening and plasticity of M42 is studied. The result shows that dislocation density

submicron carbide and ferritic grain size play different roles in work hardening and plastic instability of M42 high-speed steel. Intermediate annealing at 800°C and furnace-cooling annealing at 860°C can significantly reduce the ferrite dislocation density

restore the work hardening ability to some extent

and improve the plasticity of M42 steel. By contrast

austenitizing at 860°C followed by isothermal annealing at 750°C can obtain a large number of submicron carbides embedded in fine ferritic grains with a very low dislocation density

which is available to enhance work hardening rate and increase elongation of steel M42 to 20%.